1. Field of the Invention
The field of the invention is that of illumination. More particularly, the field of the invention is that of devices which permit persons to read and write in conditions of insufficient ambient light without disturbing others.
2. Description of Related Art
Devices are known which permit persons to read and write in the absence of ambient light. Specifically, devices are known which permit the operations of reading and writing without providing more illumination than is required for these purposes. Reading and writing in the dark without the provision of superfluous illumination may be necessary in wartime, when light discipline must be imposed to prevent detection by the enemy. An example of a device constructed for writing messages in time of war is that of Holtje, U.S. Pat. No. 2,629,043. Holtje discloses an illuminated message case which comprises a case enclosing a light source, a lucite panel, and a cellulose film having an opaque wax coating upon which the message is to be written. The Holtje device is essentially a light box in which the writing film is drawn from a built-in roller across a lucite panel which is illuminated from underneath by a battery-powered flashlight bulb.
Another device for writing in the dark designed for military purposes is that of Brassard, U.S. Pat. No. 1,279,820. Brassard discloses an illuminated note pad which consists of a casing which holds paper in position to be written on and simultaneously illuminates the paper without permitting the illumination to attract the attention of a hostile observer. A spool carries a double roll of writing paper which is drawn across a translucent plate. The translucent plate is illuminated from below by an electric lamp and reflector.
Other battery-powered light boxes which illuminate paper or cellulose film by shining light through the paper from underneath are known that are not intended for military purposes. Examples are Shofu, U.S. Pat. No. 4,184,194 and Hartmann, et al., U.S. Pat. No. 2,199,311. Shofu discloses a self-energized portable high-intensity light display unit for displaying transparencies such as x-ray films and photographic films. Hartmann, et al. disclose a map holding box containing a paddle adapted to carry a flashlight bulb and a battery for illumination of a map attached to the face of the box.
Petrie, U.S. Pat. No. 1,166,930, discloses a telescopic combined portable flashlight and writing pad which uses a pocket flashlight supplemented by a sliding sheet metal sheet holding a writing plate made of celluloid or other transparent material. The device of Petrie is intended to illuminate a sheet or scrap of paper so that it may be written upon in the dark without emitting any extraneous light and attracting attention.
Dimond, U.S. Pat. No. 1,320,537, discloses a portable illuminated sketching or writing device having a flat desk or writing surface which is preferably formed of a plate of glass, removeably carried by a suitable casing or housing in which is positioned a reflector plate, which curves upwardly from the plate of glass at one end of the housing for diffusing the light rays from a battery-powered light bulb carried by the housing at the end remote from the curved end of the reflector. The housing provides a compartment in the housing for retaining paper or other sketching materials.
Schroeder, U.S. Pat. No. 4,266,164, discloses an electro-luminescent panel assembly for use in darkness or dim light in which side-by-side light strips form an integrated light field. Non-lighted regions function as dark guidelines to guide writing on overlying sheets of material through which the integrated luminescent field is visible upon energization of the light strips.
As the references discussed above indicate, devices are needed for reading and writing in the dark and which can accomplish this purpose without emitting so much light that hostile attention is attracted. The purposes of such a device do not have to be warlike; passengers travelling in a darkened aircraft at night may wish to write notes to themselves without disturbing their companions; likewise persons writing in bed may wish to do so without awakening their bedmates.
The devices that have been devised for writing in the dark usually are clumsy, expensive, heavy, or difficult to build and use. A need exists for an improved device for writing in the dark without disturbing others.